It matters to Apple, CPUs are a very big expense for them, and the performance of their computers are very important to them.
I'm specifically worried about the performance workstation/gaming cpu market, which Broadcom Marvell, Cavium, and IBM are not major players in. It's currently AMD and Intel. Apple would need to sell a lot of macs with the new CPUs to make the R&D cost worth it and the new CPUs would have to be very fast or they won't sell macs.
(Amd, Intel, and now Apple)